In Europe since the end of the 80 's gradually increases the threat concerning an expansion of imminent xylophagen called horse-chestnut leaf miner (Cameraria ohridella) which impends to horse-chestnuts on the most areas of the continent, also including Poland. There are many methods related with this pest control, the most popular is horse-chestnut leaves picking and burning. However this method has many disadvantages which cause wasting of huge amount of potentially valuable organic mass. In the Institute of Agricultural Engineering of Agricultural University of Poznań undertook the test of fighting of the horse-chestnut leaf miner threat through the thermophilic composting of leaves with this parasite chrysalis. It has been stated that composting of mixture of leaves and sewage sludge allows to obtain well-marked thermophilic phase, indispensable to the horse-chestnut leaf miner destruction. Additionally compost of high quality was obtained, which can be applied in the municipal management or agriculture.